You'll find them all in the same range. I will say this again. On a 96 and up dont bother with one. The design and use of a spacer is for atomization of the air fuel mix. Being that your injection system is in the intake this will not change. They are designed for real TBI's and or carb's. Having a larger plenum size on these type units wont do anything, will not help, it cant. The main problem with ours is that the runner size's were the injection system is set-up is non existant to a degree, cheap version of a TPI. Its does greatly help a real TBI ( Pre 96) and a carb, but not a air throttle control. If you like the whistle they make, go ahead its the only thing it does do.
IMO the reason they make these available is the fact its been proven to work, they dont say on what, and hope people that have either heard good things about them or have used them in the past will continue to buy a piece of $5.00 piece of Aluminum with about $15.00 worth of machining for $80. Too make money I would too!
Youve pretty much used up all the boltons. Roller rockers are fairly easy to do, but will cost as much as the headers for about the same gain. You could buy a electric water-pump conversion , that would be good for up to 10 h.p. And ignition would help throttle response. And E-Ram could add another 10. Other than that you need to either internal, real S/C or ( UGH) NOS. With any luck sometime next year someone will put out and intek for us. Oh, almost forgot, your HPP 3 program is probably been overtuned, a custom flash could yeild you up to 25H.P., wont be overtuned and run somewhere in the neighborhood of $500.
ya the hpp3 is way over rated for the little bit it does, been lookin for someone to custom tune it and been wonderin about what belt to use with the electric waterpump but i will get a bigger alternator b4 that cuz at idle my new pulleys bring my volts down BIG time with the e fan going and all i would change back to the stock alt pulley but i kinda brock it when removing it, NOS is a step i am considering with a intercooler procharger or a custom intercooled vortech super charger that plus a 35-55 shot of nos should pedal my truck around pretty good, what all is involved in installing the rockers on my engine? i have donw it on older 350s but not on newer stuff much difference?
The rockers are pretty straight forward if you stay with 1:52's. Its just a bolt -on pretty much. The hardets part is getting everything outta the way to do it. Every year is a little different so you will need a chiltons or something for tightening specs.
Here look at this:
This comapny is in Buffalo and I talked with them earlier this year. I dont klnow if you can send it in, didnt ask. But for around $500 they run it on the dyno and flash it for the best they can.